Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/20—Compounding polymers with additives, e.g. colouring
  • C08J3/22—Compounding polymers with additives, e.g. colouring using masterbatch techniques
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C1/00—Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C1/00—Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition
  • B60C1/0016—Compositions of the tread
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
  • B60C11/0008—Tyre tread bands; Tread patterns; Anti-skid inserts characterised by the tread rubber
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/20—Compounding polymers with additives, e.g. colouring
  • C08J3/22—Compounding polymers with additives, e.g. colouring using masterbatch techniques
  • C08J3/226—Compounding polymers with additives, e.g. colouring using masterbatch techniques using a polymer as a carrier
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/34—Silicon-containing compounds
  • C08K3/36—Silica
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/54—Silicon-containing compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/54—Silicon-containing compounds
  • C08K5/548—Silicon-containing compounds containing sulfur
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K7/00—Use of ingredients characterised by shape
  • C08K7/22—Expanded, porous or hollow particles
  • C08K7/24—Expanded, porous or hollow particles inorganic
  • C08K7/26—Silicon- containing compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L21/00—Compositions of unspecified rubbers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L7/00—Compositions of natural rubber
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
  • B60C11/0008—Tyre tread bands; Tread patterns; Anti-skid inserts characterised by the tread rubber
  • B60C2011/0016—Physical properties or dimensions
  • B60C2011/0025—Modulus or tan delta
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2307/00—Characterised by the use of natural rubber
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K2201/00—Specific properties of additives
  • C08K2201/002—Physical properties
  • C08K2201/006—Additives being defined by their surface area
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2205/00—Polymer mixtures characterised by other features
  • C08L2205/02—Polymer mixtures characterised by other features containing two or more polymers of the same C08L -group
  • C08L2205/025—Polymer mixtures characterised by other features containing two or more polymers of the same C08L -group containing two or more polymers of the same hierarchy C08L, and differing only in parameters such as density, comonomer content, molecular weight, structure
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2205/00—Polymer mixtures characterised by other features
  • C08L2205/03—Polymer mixtures characterised by other features containing three or more polymers in a blend
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2205/00—Polymer mixtures characterised by other features
  • C08L2205/06—Polymer mixtures characterised by other features having improved processability or containing aids for moulding methods
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2310/00—Masterbatches

Definitions

• carbon black is used as a rubber reinforcing filler. This is because the carbon black can impart high wear resistance to a rubber material for a tire. However, it is difficult to obtain, by using the carbon black alone, a rubber material for a tire having a high level of balance among a wet grip property, the wear resistance, and the fuel efficiency.
• silica produced by wet-process is blended instead of the carbon black.
• a blending amount of the carbon black is relatively reduced, and thus a decrease in breaking strength and wear resistance of the rubber material for a tire is unavoidable.
• Patent Literatures 1 and 2 propose rubber materials for a tire that contain an inorganic compound powder in addition to a rubber component and carbon black and silica produced by wet-process as fillers, for the purpose of obtaining a rubber material for a tire having excellent fuel efficiency and wet grip property without decreasing wear resistance.
• Patent Literature 3 proposes a rubber material for a tire that has improved wear resistance and wet grip property by using a diene-based rubber component, silica produced by wet-process, and carbon black having a specified property such as DBP, N 2 SA, and a property calculated from two-dimensional projection image analysis of an aggregate.
• the material does not fully satisfy the fuel efficiency in addition to the wear resistance and the wet grip property.
• Patent Literature 4 proposes a vulcanized rubber composition having a predetermined relationship among a stress at 300% elongation (M300), a stress at 100% elongation (M100), a tensile strength at break (TB), and a tensile elongation at break (EB). It is disclosed that the vulcanized rubber composition has excellent wear resistance. However, a wet grip property is insufficient, and fuel efficiency is not evaluated at all.
• the rubber materials for a tire described in Patent Literatures 1 to 4 need to be blended with a relatively large amount of the inorganic compound powder in order to fully obtain the effect of improving the wet grip property and the fuel efficiency, and in this case, the wear resistance tends to be easily decreased, and thus a rubber material for a tire having a more excellent balance among the wear resistance, the fuel efficiency, and the wet grip property has not been obtained.
• the present invention has been made in view of such circumstances, and an object thereof is to provide a rubber material for a tire having a more excellent balance among wear resistance, fuel efficiency, and a wet grip property, a masterbatch and a rubber composition for a tire suitable for producing the same, methods for producing the masterbatch and the rubber composition for a tire, and a tire including a tire member made of the rubber material for a tire.
• the hydrophilic fumed silica is bulkier than the silica produced by wet-process, and thus in a Banbury mixer usually used for kneading a rubber composition, the hydrophilic fumed silica tends to scatter during kneading, and it is difficult to obtain a rubber composition in which the hydrophilic fumed silica is sufficiently dispersed.
• the present inventors have conducted further intensive studies, and as a result, have found that the above finding can be solved by using a kneading machine having a low rotor rotation speed, which is not usually used for kneading the rubber composition due to productivity.
• a rubber material for a tire having a more excellent balance among wear resistance, fuel efficiency, and a wet grip property a masterbatch and a rubber composition for a tire suitable for producing the same, methods for producing the masterbatch and the rubber composition for a tire, and a tire including a tire member made of the rubber material for a tire.
• the masterbatch according to the present embodiment is a kneaded product to be kneaded with a blending component containing at least a rubber component. That is, the masterbatch according to the present embodiment is kneaded with another blending component containing at least a rubber component to form a rubber composition for a tire.
• a content ratio of the hydrophilic fumed silica to the rubber component in the masterbatch according to the present embodiment is higher than a content ratio of the hydrophilic fumed silica to a total rubber component contained in the rubber composition for a tire. That is, a concentration of the hydrophilic fumed silica with respect to an amount of the rubber component in the masterbatch according to the present embodiment is higher than a concentration of the hydrophilic fumed silica with respect to an amount of the rubber component in the rubber composition for a tire.
• the masterbatch according to the present embodiment is a kneaded product containing the hydrophilic fumed silica at a high concentration.
• the rubber component contained in the masterbatch according to the present embodiment is at least one selected from the group consisting of a natural rubber and a synthetic rubber. That is, the rubber component contained in the masterbatch may contain only a natural rubber, only a synthetic rubber, or both a natural rubber and a synthetic rubber.
• the natural rubber examples include a natural rubber (NR) and a modified natural rubber such as an epoxidized natural rubber (ENR), a hydrogenated natural rubber (HNR), a deproteinized natural rubber (DPNR), and a high-purity natural rubber (HPNR). These natural rubbers may be used alone or in combination of two or more types thereof. In the present embodiment, an NR is preferred as the natural rubber.
• NR natural rubber
• EMR epoxidized natural rubber
• HNR hydrogenated natural rubber
• DPNR deproteinized natural rubber
• HPNR high-purity natural rubber
• a content of the NR in the rubber component (100 parts by mass) contained in the masterbatch is preferably 30 parts by mass or more, and more preferably 40 parts by mass or more, for the reason of improving wear resistance.
• the content of the NR is preferably 80 parts by mass or less, and more preferably 75 parts by mass or less, for the reason of exhibiting a balance among tire properties, which are features of the present invention.
• an isoprene rubber (IR), a butadiene rubber (BR), a styrene-butadiene rubber (SBR), a styrene-isoprene-butadiene rubber (SIBR), an ethylene-propylene-diene rubber (EPDM), a chloroprene rubber (CR), an acrylonitrile-butadiene rubber (NBR), or the like can be used.
• These synthetic rubbers may be used alone or in combination of two or more types thereof. In the present embodiment, an SBR and a BR are preferred as the synthetic rubber.
• the SBR is not particularly limited, and examples thereof include an unmodified solution-polymerized SBR (S-SBR), an unmodified emulsion-polymerized SBR (E-SBR), and a modified SBR thereof (modified S-SBR and modified E-SBR).
• S-SBR solution-polymerized SBR
• E-SBR unmodified emulsion-polymerized SBR
• modified SBR thereof modified S-SBR and modified E-SBR
• the BR is not particularly limited, and for example, a BR containing a syndiotactic polybutadiene crystal can be used.
• a product of the BR containing the syndiotactic polybutadiene crystal include a high-cis BR such as BR1220 manufactured by Zeon Corporation and BR130B and BR150B manufactured by Ube Corporation, and VCR412 and VCR617 manufactured by Ube Corporation.
• a content of the BR in the rubber component (100 parts by mass) contained in the masterbatch is preferably 20 parts by mass or more, and more preferably 30 parts by mass or more, for the reason of improving the wear resistance.
• the content of the BR is preferably 50 parts by mass or less, and more preferably 40 parts by mass or less, for the reason that heat generation inside the tire can be reduced.
• the fumed silica is divided into hydrophilic fumed silica and hydrophobic fumed silica based on a property with respect to water.
• Silanol groups are present on a surface of the fumed silica.
• the silanol groups are chemically active and particularly easily react with water. Therefore, a surface treatment (hydrophobization treatment) of lowering reactivity with water by reacting the silanol groups with another substance may be performed.
• the fumed silica subjected to a hydrophobization treatment is called hydrophobic fumed silica
• the fumed silica not subjected to a hydrophobization treatment is called hydrophilic fumed silica.
• the fumed silica contained in the masterbatch according to the present embodiment is hydrophilic fumed silica.
• the hydrophilic fumed silica forms a structure caused by the fumed silica more easily than the hydrophobic fumed silica. It is considered that since such a structure is present in a rubber material for a tire obtained by vulcanizing the rubber composition for a tire, the wear resistance of the rubber material for a tire is improved. On the other hand, the hydrophobic fumed silica has fewer such structures and tends to have insufficient improvement in wear resistance.
• a tap density of the hydrophilic fumed silica is preferably less than 200 g/L, more preferably 150 g/L or less, and even more preferably 100 g/L or less.
• the tap density of the hydrophilic fumed silica may be 200 g/L or more, and a compression treatment is usually required to increase the tap density of the hydrophilic fumed silica to 200 g/L or more. Therefore, there is a problem that an extra step is required and a cost is increased.
• a lower limit of the tap density of the hydrophilic fumed silica is not particularly limited, and from a viewpoint of production, the lower limit of the tap density is, for example, 30 g/L.
• a BET specific surface area of the hydrophilic fumed silica is preferably 50 m 2 /g or more, 80 m 2 /g or more, 120 m 2 /g or more, 200 m 2 /g or more, 250 m 2 /g or more, 300 m 2 /g or more, or 350 m 2 /g or more.
• the BET specific surface area of the fumed silica is within the above range, in the hydrophilic fumed silica, the number of the silanol groups serving as a reaction site with the rubber component or the silane coupling agent can be sufficiently secured. As a result, the hydrophilic fumed silica and the rubber component can be kneaded well.
• An upper limit of the BET specific surface area of the hydrophilic fumed silica is not particularly limited, and is, for example, 500 m 2 /g.
• the BET specific surface area of the hydrophilic fumed silica is too small, it is necessary to increase a flame temperature at the time of producing the fumed silica, the structure unique to the fumed silica is lost, and it tends to be impossible to stably produce the fumed silica.
• the BET specific surface area of the hydrophilic fumed silica is too large, stable production tends to be impossible.
• a blending amount of the hydrophilic fumed silica is 13 parts by mass or more to 130 parts by mass or less with respect to 100 parts by mass of the rubber component. That is, the masterbatch according to the present embodiment can contain, at a high concentration, the hydrophilic fumed silica which is difficult to be kneaded and hardly dispersed in the rubber component. Therefore, by producing the rubber composition for a tire using the masterbatch, the rubber material for a tire having excellent wear resistance can be easily obtained.
• the blending amount of the hydrophilic fumed silica is more preferably 15 parts by mass or more, and even more preferably 20 parts by mass or more, with respect to 100 parts by mass of the rubber component.
• the blending amount of the hydrophilic fumed silica is more preferably 110 parts by mass or less, and even more preferably 100 parts by mass or less, with respect to 100 parts by mass of the rubber component.
• the silane coupling agent is not particularly limited as long as the silane coupling agent is usually used in the rubber composition.
• a sulfur-containing silane coupling agent is preferred.
• the sulfur-containing silane coupling agent include bis-(3-triethoxysilylpropyl) tetrasulfide, bis(3-triethoxysilylpropyl) disulfide, 3-trimethoxysilylpropylbenzothiazole tetrasulfide, ⁇ -mercaptopropyltriethoxysilane, 3-octanoylthiopropyltriethoxysilane, or a mercapto-thiocarboxylate oligomer.
• a mercaptosilane of the linking unit B is covered with -C 7 H 15 of the linking unit A, so that a scorch time can be prevented from being shortened and good reactivity with the hydrophilic fumed silica and the rubber component can be secured.
• Specific examples of the mercapto-thiocarboxylate oligomer include "NXT-Z45" manufactured by Momentive.
• the blending amount of the silane coupling agent is more preferably 1.5 parts by mass or more, and even more preferably 2 parts by mass or more, with respect to 100 parts by mass of the rubber component.
• the blending amount of the silane coupling agent is more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less, with respect to 100 parts by mass of the rubber component.
• the masterbatch in addition to the above components (the rubber component, the hydrophilic fumed silica, and the silane coupling agent), the masterbatch may also contain a component to be blended into the rubber composition.
• a component to be blended into the rubber composition examples include a lubricant.
• a lubricant When the masterbatch contains a lubricant, a kneading property of the masterbatch is improved.
• Examples of the lubricant include stearic acid and a process oil.
• the lubricant may be used alone, or may be used in a combination of two or more types thereof.
• Examples of the process oil include an aroma oil, a paraffin oil, and a naphthene oil. These may be used alone, or may be used in a combination of two or more types thereof.
• a blending amount of the lubricant is not limited as long as an effect of the present invention is obtained.
• the blending amount of the lubricant is preferably 1 part by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the rubber component.
• the blending amount of the lubricant is more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more, with respect to 100 parts by mass of the rubber component.
• the blending amount of the lubricant is more preferably 35 parts by mass or less, and even more preferably 30 parts by mass or less, with respect to 100 parts by mass of the rubber component.
• the masterbatch may contain a reinforcing filler in addition to the hydrophilic fumed silica.
• a reinforcing filler examples include carbon black, silica produced by wet-process, clay, mica, talc, calcium carbonate, aluminum hydroxide, aluminum oxide, and titanium oxide.
• a filler coupling agent can also be blended in an appropriate amount.
• a blending amount of the reinforcing filler is not limited as long as the effect of the present invention can be obtained, and may be a general blending amount.
• the masterbatch according to the present embodiment is obtained by kneading the above rubber component, the above hydrophilic fumed silica, the above silane coupling agent, and other components as necessary.
• a content thereof in the total rubber component is preferably 30 parts by mass or more, and more preferably 40 parts by mass or more, for the reason of improving the wear resistance.
• the content of the NR is preferably 80 parts by mass or less, and more preferably 75 parts by mass or less, for the reason of exhibiting a balance among tire properties, which are features of the present invention.
• a content thereof in the total rubber component is preferably 20 parts by mass or more, and more preferably 30 parts by mass or more, for the reason of improving the wear resistance.
• the content of the BR is preferably 50 parts by mass or less, and more preferably 40 parts by mass or less, for the reason that heat generation inside the tire can be reduced.
• a blending amount of the hydrophilic fumed silica is 5 parts by mass or more and 90 parts by mass or less with respect to 100 parts by mass of the above rubber component.
• the wear resistance performance of the obtained rubber material for a tire tends to be insufficient.
• the blending amount of the hydrophilic fumed silica is too large, the hydrophilic fumed silica is not sufficiently dispersed in the rubber component, and a good kneaded product tends not to be obtained.
• a range of the BET specific surface area of the hydrophilic fumed silica is preferably the same as the range of the BET specific surface area of the hydrophilic fumed silica contained in the masterbatch described above.
• a blending amount of the silane coupling agent is 1.5 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the above rubber component.
• the blending amount of the silane coupling agent is too small, dispersibility of a silica compound such as the hydrophilic fumed silica in the rubber composition for a tire tends to be easily insufficient.
• the blending amount of the silane coupling agent is too large, there is a concern that silane coupling agents are easily subjected to condensation, and the wear resistance of the obtained rubber material for a tire cannot be sufficiently improved.
• the blending amount of the silane coupling agent is preferably 2.0 parts by mass or more, and more preferably 2.5 parts by mass or more, with respect to 100 parts by mass of the above rubber component.
• the blending amount of the silane coupling agent is preferably 25 parts by mass or less, and more preferably 20 parts by mass or less, with respect to 100 parts by mass of the above rubber component.
• the rubber composition for a tire according to the present embodiment preferably contains the above masterbatch. That is, the rubber composition for a tire according to the present embodiment is preferably produced using the above masterbatch.
• a rubber composition for a tire containing a predetermined amount of the hydrophilic fumed silica which is difficult to be kneaded and dispersed is easily obtained.
• the rubber composition for a tire may also contain a component to be blended into the rubber composition.
• the rubber composition for a tire preferably contains silica produced by wet-process.
• the silica produced by wet-process is generally silica synthesized by a neutralization reaction of sodium silicate and a mineral acid (usually sulfuric acid).
• the silica produced by wet-process is generally classified into precipitated silica and gel silica.
• the silica produced by wet-process is preferably precipitated silica.
• the amount of water adsorbed to silanol groups on a surface of the silica produced by wet-process is larger than that of the fumed silica. It is considered that the adsorbed water prevents a crosslinked structure from being formed. Therefore, the amount of the silica produced by wet-process required for an effect caused by the crosslinked structure via the silanol groups is larger than the amount of the fumed silica. In other words, in order to achieve the same effect as the effect achieved by the fumed silica, a blending amount of the silica produced by wet-process is larger than the blending amount of the fumed silica.
• the silica produced by wet-process has a BET specific surface area smaller than the fumed silica, the blending amount of the silica produced by wet-process required to achieve target hardness of the rubber material for a tire tends to be large.
• the silica produced by wet-process may be mixed with the fumed silica before the step of kneading with the above rubber component, or may be added in the step of kneading the fumed silica and the above rubber component.
• TB ⁇ EB/M100 MPa ⁇ %/MPa
• fuel efficiency and a wet grip property of the rubber material for a tire are also preferably influenced.
• TB ⁇ EB/M100 is more preferably 4,400 MPa ⁇ %/MPa or more and 11,000 MPa ⁇ %/MPa or less, and even more preferably 5,600 MPa ⁇ %/MPa or more and 9,000 MPa ⁇ %/MPa or less.
• a Mooney viscosity at 100°C (ML1+4, 100°C) of the obtained test piece made of the rubber composition for a tire was measured in accordance with JIS K6300-1 using a Mooney viscosity meter (VR-1132 manufactured by Ueshima Seisakusho Co., Ltd.). When the Mooney viscosity is low, the workability of the rubber composition for a tire tends to be good. The results are shown in Table 2.
• the obtained rubber composition for a tire was press-vulcanized at 160°C for 10 minutes to obtain a rubber material for a tire.
• a test piece for performing the following evaluations on the obtained rubber material for a tire was prepared. The obtained test piece was used to evaluate the following physical properties.
• a hardness (Shore A hardness) of the obtained test piece made of the rubber material for a tire was measured in accordance with JIS K6253 Type A by a durometer.
• the target A hardness of the rubber material for a tire varies depending on an application of a tire.
• the A hardness of the test piece was changed in Standard Examples and Examples, and the hardness was adjusted to be approximately the same. The results are shown in Table 2.

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• 2023
  • 2023-10-11 EP EP23879675.9A patent/EP4588960A1/de active Pending
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  • 2023-10-11 KR KR1020257010056A patent/KR20250088707A/ko active Pending
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